An electronic slug rejector which is highly effective in distinguishing authentic coins from slugs, and which also is highly effective in distinguishing between those authentic coins, is shown and described in U.S. application Ser. No. 913,161 which was filed on July 6, 1978 and which issued June 30, 1981 as U.S. Pat. No. 4,275,806 and which corresponds to Japanese application Ser. No. 66,971/77 which was filed on June 7, 1977, in U.S. application Ser. No. 913,165 which was filed on June 6, 1978 and which issued Mar. 24, 1981 as U.S. Pat. No. 4,257,435 and which corresponds to Japanese application Ser. No. 66,973/77 which was filed on June 7, 1977, in U.S. application Ser. No. 913,275 which was filed on June 7, 1978 and which issued Oct. 21, 1980 as U.S. Pat. No. 4,228,811 and which corresponds to Japanese application Ser. No. 66,972/77 which was filed on June 7, 1977, in U.S. application Ser. No. 917,429 which was filed on June 20, 1978 and which issued June 10, 1980 as U.S. Pat. No. 4,206,775 and which corresponds to Japanese application Ser. No. 73,726/77 which was filed on June 21, 1977, and/or in U.S. application Ser. No. 928,023 which was filed on July 25, 1978 and which corresponds to Japanese application Ser. No. 89095/77 which was filed on July 25, 1977. That electronic slug rejector has an authenticity-determining magnetic coil which serves as one leg of a plurality of Wien bridges, it has a light-sensitive element which is mounted in advanced of that authenticity-determining coil to detect objects rolling toward that authenticity-determining coil, and it has a light-sensitive element which is mounted beyond that authenticity-determining coil to detect objects rolling away from that authenticity-determining coil. Although that electronic slug rejector is highly effective, it may occasionally accept a copper slug that has dimensions which enable it to interact with the authenticity-determining magnetic coil to cause that authenticity-determining coil to produce an output which is similar to the output that an authentic coin causes that authenticity-determining coil to produce.